Headmaster Leopold's heart seized. He immediately realized his mistake. If Ryu hadn't known who he was from the very beginning, would he have been able to goad him into anger so quickly? Even further, would Ryu be so confident that he wouldn't kill him? The answer to both were resounding no's.
Ryu knew that Leopold had disappointing disciples only because he knew who Leopold was. Ryu also knew that Leopold wouldn't strike hard enough to kill him because he already guessed that Leopold had some insight into the fact he had a pair of Heavenly Pupils due to the battle against the Ice Eyed Bear. He even knew something as seemingly useless as Leopold's dominant hand. Had Leopold not been so cocky, Ryu wouldn't have been bold enough to gamble with his life in such a way!
'Dammit!' Leopold's foot struck the ground as he surged toward the Immortal Path. 'It doesn't matter, do you think the Immortal Path is a joke? Even I must take it seriously!'